This invention relates generally to percutaneous electrical therapy systems for medical use. In particular, the invention relates to a holding mechanism for holding a percutaneous electrode in place after insertion.
Electrical therapy has long been used in medicine to treat pain and other conditions. For example, transcutaneous electrical nerve stimulation (TENS) systems deliver electrical energy through electrode patches placed on the surface of a patient""s skin to treat pain in tissue beneath and around the location of the patches. The efficacy of TENS systems in alleviating pain is questionable at best, however.
More recently, a technique in which electrodes are placed through the patient""s skin into the target tissue has been proposed. Percutaneous Neuromodulation Therapy (xe2x80x9cPNTxe2x80x9d) (also sometimes called Percutaneous Electrical Nerve Stimulation or xe2x80x9cPENSxe2x80x9d) using percutaneously placed electrodes achieves significantly better pain relief results than TENS treatments using skin surface electrodes. This therapy is described in Ghoname et al., xe2x80x9cPercutaneous Electrical Nerve Stimulation for Low Back Pain,xe2x80x9d JAMA 281:818-23 (1999); Ghoname et al., xe2x80x9cThe Effect of Stimulus Frequency on the Analgesic Response to Percutaneous Electrical Nerve Stimulation in Patients with Chronic Low Back Pain,xe2x80x9d Anesth. Analg. 88:841-6 (1999); Ahmed et al., xe2x80x9cPercutaneous Electrical Nerve Stimulation (PENS): A Complementary Therapy for the Management of Pain Secondary to Bony Metastasis,xe2x80x9d Clinical Journal of Pain 14:320-3 (1998); and Ahmed et al., xe2x80x9cPercutaneous Electrical Nerve Stimulation: An Alternative to Antiviral Drugs for Herpes Zoster,xe2x80x9d Anesth. Analg. 87:911-4 (1998). The contents of these references are incorporated herein by reference.
Thus far, PNT practitioners have used percutaneously placed acupuncture needles attached to waveform generators via cables and alligator clips to deliver the therapy to the patient. This arrangement and design of electrodes and generator is far from optimal. For example, percutaneously placed electrodes can move or back out of position in response, e.g., to muscle contractions in the patient or a pulling force from an attached electrical cable. The position of the electrode""s point can affect the efficacy of the treatment. It is therefore an object of this invention to provide a holding mechanism for percutaneous electrodes.
It is a further object of this invention to provide a percutaneous electrical therapy system having electrodes and electrode assemblies that are safe, efficacious, inexpensive and easy to use.
Other objects of the invention will be apparent from the description of the preferred embodiments.
The invention is a percutaneous electrical therapy system with electrode position maintenance. In a preferred embodiment, the system includes a control unit; an electrode electrically connectable to the control unit, the electrode having a sharp point at a distal end adapted to be inserted into a patient""s tissue; and an inserted electrode holding mechanism adapted to hold the electrode in place after insertion of the sharp point of the electrode into the patient""s tissue. The inserted electrode holding mechanism may include an electrode handle attached to the electrode and adapted to be exterior to the patient""s tissue after insertion of the sharp point into the patient""s tissue.
The inserted electrode holding mechanism may also include a holding element adapted to be attached to the patient and to the electrode, such as a patch adapted to mechanically interact with at least a portion of the electrode. In some embodiments, the patch may have an aperture, with the inserted electrode holding mechanism also having an electrode handle attached to the electrode and adapted to mechanically interact with the patch aperture. The system may also include an introducer adapted to insert the electrode through the patch aperture and to cause the electrode handle and the patch aperture to mechanically interact.
In some embodiments, the system includes an electrode assembly of which the inserted electrode holding mechanism is a part, the electrode and the holding element, the electrode assembly being operable to insert the electrode into the patient""s tissue and being adapted to attach to the patient. The electrode assembly may have a movable actuator adapted to move the electrode from an uninserted position to an inserted position, with the inserted electrode holding mechanism including an actuator holding mechanism adapted to hold the actuator in place when the electrode is in its inserted position. The system may also have an actuator tool adapted to move the actuator and the electrode from the uninserted position to the inserted position. The actuator tool may be further adapted to move the actuator and the electrode from the inserted position to the uninserted position.
The system may include a conductor connecting the electrode and the control unit, wherein the inserted electrode holding mechanism is further adapted to provide strain relief to the electrode.
The invention is also a method of providing electrical therapy, the method including the steps of inserting an electrode into a patient; using an inserted electrode holding mechanism to hold the inserted electrode in place in the patient; and applying an electrical signal to the electrode from a control unit. In some embodiments, the inserted electrode holding mechanism has a holding element, with the method further including the step of attaching the holding element to the patient. The holding element may be a patch, with the using step including the step of mechanically interacting at least a portion of the electrode with the patch. The holding element may also be a housing, the inserting step including the step of moving the electrode within the housing. The inserting step may also include the step of moving an actuator within the housing, with the using step including the step of mechanically interacting the actuator with the housing to hold the inserted electrode in place in the patient.
The invention is described in further detail below with reference to the drawings.